[17a-Z23-1~11] 12.2 Characterization and Materials Physics

△ [17a-Z23-6] Direct observation of photoexcited electron dynamics in TADF process of 4CzIPN solid-state film using time-resolved photoemission electron microscopy

〇Yusuke Fukami¹, Masato Iwasawa¹, Takuya Hosokai², Hajime Nakanotani³, Keiki Fukumoto⁴, Yoichi Yamada¹ (1.Tsukuba Univ., 2.AIST, 3.Kyusyu Univ., 4.KEK)

Keywords:Thermally activated delayed fluorescence, Time-resolved photoemission electron microscopy, Photoexcited electron dynamics

Recent studies have shown that the solid-state film of thermally activated delayed fluorescence (TADF) molecules can be used as an efficient emitter layer. It is therefore important to elucidate the fundamental properties of TADF solid-state film. Herein, the photoexcited electrons dynamics in the TADF process of the 4CzIPN solid-state film was examined by time-resolved photoelectron emission microscopy (TR-PEEM) to clarify the photophysical processes including an exciton dissociation in the TADF solid-state film. We were able to follow the exciton deactivation process corresponding to prompt and delayed fluorescence observed by TR-PL measurement. Furthermore, we estimated the dissociation rate of the excitons to be roughly 8%.